Magnetism in Co-doped rutile TiO2 nanoparticles

We studied the magnetic properties of xx at.% Co-doped rutile TiO2 nanoparticles (with x=1.0,3.0,5.0x=1.0,3.0,5.0) synthesized by the sol–gel technique. The obtained experimental results revealed that all the samples exhibited the ferromagnetic behavior at room temperature. The ferromagnetic order increased with increasing the Co content, whereas the coercivity force HcHc decreased. The zero-field-cooled and field-cooled magnetizations versus temperature showed a peak at about 40 K, which was assigned to be from an antiferromagnetic phase CoTiO3. The presence of this phase was also confirmed by X-ray diffraction patterns for the 3.0 and 5.0 at.% Co-doped samples. By means of X-ray absorption fine structure study, we suggested that the room-temperature ferromagnetism in Co-doped TiO2 nanoparticles was generated from Co2+ ions present in the TiO2 host lattice.